Maxillofacial bone augmentation is needed in many situations including alveloar ridge augmentation (including horizontal and vertical ridge augmentation, in extraction sockets, in repair of bone sockets and deficiencies in the bony wall of the maxillary sinus.
Guided bone regeneration (GBR) is a regenerative procedure derived from guided tissue regeneration (GTR) around natural teeth and used for ridge augmentation prior to or in conjunction with osseointegrated implant placement. Originally, the biological principle of guided tissue regeneration was discovered by Nyman and Karring in the early 1980's. The surgical technique involves the placement of a cell occlusive barrier membrane to protect the blood clot and to create a secluded space around the bone defect to allow bone regeneration without competition from other tissues.
Schenk et al. (Int. J. Oral Maxillofac. Implants 1994; 9(1); 13-29) demonstrated how the newly regenerated bone progresses in a programmed sequence through a series of biological steps that closely parallel the pattern of normal bone growth and development. These findings have been confirmed by Simion et al. (Clin. Oral Implants Res. 1999; 10(2):73-84) with the same canine model using polytetrafluoroethylene (ePTFE) titanium-reinforced membranes. Evidence emerging from clinical studies also suggests that regenerated bone is capable of withstanding the occlusal loading exerted by functional forces, and is hence stable over time. (Mayfield et al. (Clin. Oral Implants Res. 1998; 9(5)297-302)).
GBR is well documented and studies demonstrate its high efficacy and predictability in horizontal and vertical ridge augmentation procedures. This last procedure, which is believed to be the most technically demanding of all GBR techniques, was first proposed by Simion et al. (Int. J. Periodontic Restorative Dent. 1994; 14(6):496:511) in 1994. It is indicated when bone height is insufficient for implant placement, long-term stability, or when prosthetic rehabilitation will result in excessively long crowns and an unfavorable implant/crown ratio.
A variety of materials are available for bone substitutes and membranes when applying the GBR principles. Human clinical studies have shown the possibility of successful vertical bone augmentation using e-PTFE membranes in combination with filling materials (autogenous bones (Tinti, et al., Int. J. Periodontics Restorative Dent. 1996; 16(3):220-9, Tinti, et al., Int. J. Periodontics Restorative Dent. 1998; 18(5):434-43)) and demineralized freeze-dried bone allograft (DFDBA), (Simion, et al., Int. J. Periodontics Restorative Dent. 1998; 18(1):8-23)).
One of the major issues concerning alveolar ridge augmentation procedures is the premature membrane exposure due to soft tissue dehiscence resulting in local infection and incomplete bone regeneration, jeopardizing the final results. In order to overcome these problems, the materials used and the surgical techniques applied in GBR have frequently been modified and adapted (Simion et al., Int. J. Periodontics Restorative Dent. 1994; 14(2):166-80, Simion et al, J. Clin. Periodontol. 1995; 22(4); 321-31).
Vertical ridge augmentation is needed for both the mandible and maxilla. Accordingly, what is needed are new methods and materials that are free of problems associated with prior art methods, and that are effective in augmenting bone, particularly augmentation maxillofacial bones, and particularly the alveolar ridge so that stable osseointegrated implants may be achieved.